Theorem chub1i

Description: CH join is an upper bound of two elements. (Contributed by NM, 15-Oct-1999) (New usage is discouraged.)

	Ref	Expression
Hypotheses	ch0le.1	|- A e. CH
	chjcl.2	|- B e. CH
Assertion	chub1i	|- A C_ ( A vH B )

Proof

Step	Hyp	Ref	Expression
1		ch0le.1	|- A e. CH
2		chjcl.2	|- B e. CH
3	1	chshii	|- A e. SH
4	2	chshii	|- B e. SH
5	3 4	shub1i	|- A C_ ( A vH B )